Ultrasonic digitizer and host

ABSTRACT

A computing system comprises a processor and internal peripheral devices, and a system bus connecting the internal peripheral devices to the processor. One of the internal peripheral devices is an ultrasonic digitizer that digitizes ultrasonic signals from at least two associated microphones into a digitized audio signal carrying a corresponding location and outputs the digitized audio as a signal on the system bus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 12/811,702 filed on Sep. 16, 2010, which is a National PhaseApplication of International Application No. PCT/IL2009/000014 filed onJan. 4, 2009, which claims priority from U.S. Provisional ApplicationNo. 61/006,267 filed on Jan. 3, 2008, all of which are incorporated byreference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to anultrasonic digitizer and host.

Currently there are products which have a digitizer integrated into ahost, whether a laptop or desktop computer, or in a more generalizedform: a host. Furthermore there are acoustic digitizers provided asexternal peripherals that may be added to the host, as add-on's.

The suggestion is known to embed an ultrasonic receiver inside a mobilephone or a “smart phone”.

There are numerous technologies, that support digitizing, particularlyof handwriting:1) RF tablets: companies, such as Wacom, Acecad, and N-trig, use a padwith an antenna to emit RF energy to a stylus that is located above thepad. This is unsatisfactory since a computer needs a retractable pad,and this makes usage cumbersome. A built-in RF solution has noadvantages in contrast with an add-on solution having the sameproperties.2) Optical sensor: Anoto is the owner of a technology which uses aspecial paper with imprinted dots. The stylus has a camera to decode itslocation based on the dots it sees. In this technology, there is no needto embed the receiver inside the host since it uses standard RFprotocols such as Bluetooth to communicate with its host. However, thespecial paper, bulkiness of the pen and the price, are limiting factorsfor this technology.3) Ultrasonic sensor: there are several companies that use ultrasonicTOA measurement to estimate a location of a stylus. Pegasus (Pegatech),Navisis, Virtual ink and others are examples. The enabling technologyfor these products uses acoustic pulses for measuring, the TOA. Acoustictechnology has advantages in relation to the previous two technologiesdescribed above, namely it can operate on any surface and can allow 3/Dapplications. However, the known art has inter alia the followingdisadvantages:

a. Inferior accuracy and resolution

b. Size of receiver

c. Susceptibility to ultrasonic noise

d. Susceptibility to other users in the vicinity using the sametechnology

e. Relatively low sampling rate

f. Delay between writing and digital representation

On the other hand, there are benefits to having handwriting digitizationon a computer, for example the following abilities may be obtained:

1) Transferring handwritten notes to a digital format.

2) Controlling the computer (the stylus being used as a mouse).

3) Direct digital input for sketches and drawings.

4) Notes insertion to existing documents, in the same way one can writenotes on a printed document.

5) Form filling.

6) 3/D applications.

The following documents were published after the priority date of thepresent application and thus their prior art effect on the presentclaims depends on the specific jurisdiction.

WO2008018757 discloses a position-tracing-signal generating apparatusand an input system including a position-tracing input apparatus forinputting information by tracing the position of theposition-tracing-signal generating apparatus. Theposition-tracing-signal generating apparatus is capable of inputtingaccurately information on the position-tracing by emitting aultrasonic-wave signal through a guide path formed between a guide partand a ultrasonic-wave signal generating unit in only a paper surfacedirection irrespective of usage of the position-tracing-signalgenerating apparatus by user. In addition, according to the position-tracing-signal generating apparatus, a plurality of ultrasonic-wavegenerating members are provided in the ultrasonic-wave signal generatingunit, and the ultrasonic-wave generating members sequentially generateultrasonic-waves in a predetermined time interval calculated based onseparation distances between the ultrasonic-wave generating members sothat the ultrasonic-wave signal can be amplified through superpositionof the ultrasonic waves generated by the ultrasonic-wave generatingmembers. Accordingly, the position-tracing-signal generating apparatuscan also stably transmit the ultrasonic-wave signal to anultrasonic-wave signal receiving sensor disposed at a long distance.

WO2008048036 teaches a 3D position tracking method and apparatus. The 3Dposition tracking method and apparatus measures a 3D position of asignal generator by using distances between a signal generator andultrasonic signal receivers calculated by using differences between atime at which an ultrasonic signal is generated by the signal generatorand times at which the ultrasonic signal is received to the ultrasonicsignal receivers that are disposed at predetermined intervals to receivethe ultrasonic signal, and distances between the ultrasonic signalreceivers. Accordingly, a 3D position of a moving object in a 3D spacecan be accurately measured without excessive costs, and a 3D positiontracking method and apparatus as described therein can be applied to a3D mouse, a 3D pointer, a 3D video game input device, and the like.

SUMMARY OF THE INVENTION

The present embodiments relate to the incorporation of an acousticdigitizer as a built-in component into a host.

According to an aspect of some embodiments of the present inventionthere is provided a computing system comprising a processor and internalperipheral devices, and a system bus connecting said internal peripheraldevices to said processor, wherein one of said internal peripheraldevices comprises an ultrasonic digitizer configured for digitization ofultrasonic frequencies, said digitizer digitizing ultrasonic signalsfrom at least two associated microphones into a corresponding digitizedaudio output and outputs said digitized audio output as a signal on saidsystem bus.

In an embodiment, said digitized audio output comprises a decodedpositioning device location.

An embodiment may comprise an internal codec, wherein said ultrasonicdigitizer is connected to said internal codec to use said internal codecto decode said locations.

An embodiment may comprise a stylus, the stylus incorporating anultrasonic transmitter for transmitting its location to said associatedmicrophones to allow user interaction with said computer system, thestylus further comprising a tip for pointing over a surface.

In an embodiment, said tip is a writing tip, and is ink enabled to writeon paper, and said system comprises an accommodation assembly foraccommodating paper in a defined relationship with said system.

An embodiment may comprise a host computer housing, wherein said paperaccommodation system comprises a paper alignment structure, said paperalignment structure comprising a configuration that holds paper in afixed relationship with said at least two microphones.

In an embodiment, said paper alignment structure is built onto saidhousing. In an embodiment, said paper alignment structure configures apart of said housing as a writing pad.

In an embodiment, said housing comprises a keyboard and a covering isextendable over said keyboard to form said writing pad.

In an embodiment, said paper alignment structure comprises a first setof at least two microphones about one side thereof and a second set ofat least two microphones about a second side thereof and a selector forselecting between microphones of said respective sides depending onwhich are receiving a clearer signal.

In an embodiment, said housing comprises a recharging holder for astylus.

In an embodiment, said paper alignment structure comprises a tensionedclip to hold paper against said housing.

In an embodiment, said tension is one member of the group consisting ofrotary tension and linear tension.

In an embodiment, said paper alignment structure comprises a retractablepaperweight, said at least two microphones being built into saidpaperweight, said paperweight being attached via a cord to said host.

An embodiment may comprise a third microphone for three-dimensionallocation.

A configuration may use said three-dimensional location to compensatefor a height of paper in calculating said location.

The system may be such that activation of said digitizer switches saidcomputing system from a dormant to an active state.

In an embodiment, said digitizer comprises a memory that stores userinput while said computing system is in a dormant state, which userinput is subsequently accessible by said computing system.

The system may be configured to accept input from said digitizer whileremaining in an otherwise dormant state.

The system may be configured with a calibration mechanism for detectingsize and direction of handwriting and deducing a location or orientationof paper.

An embodiment may comprise a computer housing and wherein said at leasttwo microphones are in a fixed relationship with respect to saidhousing.

According to a second aspect of the present invention there is provideda computing system comprising a processor having a system clock, and apositioning unit for providing positioning of a positioning device,wherein said processor comprises a codec that digitizes ultrasonicsignals of said positioning device received via at least two associatedmicrophones, to provide said processor with a signal further processableinto a corresponding positioning device location, and a synchronizationunit for synchronizing said system clock for said provided positioning.

In an embodiment, said codec is external to said processor, the systemfurther comprising a decimation filter in parallel with said codec.

An embodiment may comprise a wireless unit that synchronizes with apointing device, which unit is further configured for receiving datafrom an additional microphone.

An embodiment may be configured to use a location signal modulated ontoa continuous ultrasonic carrier.

An embodiment may comprise a screen and wherein said at least twoassociated microphones are fixed about said screen to provide atouchscreen application.

In an embodiment the CODEC is internal to said processor.

In an embodiment, said CODEC is external to said processor and whereinsaid synchronizing for said provided positioning comprises synchronizingsaid CODEC with said system clock.

In an embodiment, the system comprises a wireless transceiver forsynchronization with a pointing device, and said synchronizing for saidprovided positioning comprises synchronizing said system clock to saidwireless transceiver.

In an embodiment, said wireless unit is a system internal unit forwireless networking.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

For example, hardware for performing selected tasks according toembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to embodiments of theinvention could be implemented as a plurality of software instructionsbeing executed by a computer using any suitable operating system. In anexemplary embodiment of the invention, one or more tasks according toexemplary embodiments of method and/or system as described herein areperformed by a data processor, such as a computing platform forexecuting a plurality of instructions. Optionally, the data processorincludes a volatile memory for storing instructions and/or data and/or anon-volatile storage, for example, a magnetic hard-disk and/or removablemedia, for storing instructions and/or data. Optionally, a networkconnection is provided as well. A display and/or a user input devicesuch as a keyboard or mouse are optionally provided as well.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a simplified schematic diagram illustrating a computer systemthat incorporates an ultrasonic digitizer according to a firstembodiment of the present invention;

FIG. 2 is a simplified schematic diagram illustrating an ultrasonicstylus for use with the ultrasonic digitizer of FIG. 1;

FIG. 3 is a simplified schematic diagram illustrating a location systemcomprising the digitizer of FIG. 1, the stylus of FIG. 2 and amicrophone array;

FIG. 4 is a simplified schematic diagram showing how an internal surfaceof the host of FIG. 1 can be used for paper location;

FIGS. 5A and 5B are schematic diagrams which illustrate an embodiment ofthe present invention in which the weight of the host is used to holdpaper in position via a clip;

FIGS. 6A and 6B are schematic diagrams showing an alternativeconstruction of the clip of FIGS. 5A and 5B in which the tension on theclip is rotary;

FIG. 7 is a schematic diagram in which a paper weight attached by a cordis used to hold the paper and is then retracted into a receptacle on thehousing of the host;

FIG. 8 is a schematic diagram showing an embodiment of the presentinvention in which the microphones are mounted in the housing around thescreen, and the stylus interacts with active regions in the screen;

FIG. 9 is a schematic diagram showing an architecture for deepintegration of the ultrasonic location system into a host, wheredetermination of the location is carried out by the processor and aninternal codec;

FIG. 10 is a schematic diagram illustrating a variation of theembodiment of FIG. 9 in which a transmitter used for synchronizationaccepts data from a third microphone;

FIG. 11 is a schematic diagram illustrating a variation in which adecimation filter is placed in parallel with the codec to deal withcases in which the codec is not optimized for ultrasonic frequencies;and

FIG. 12 is a schematic diagram illustrating an integration of apositioning system according to the above embodiments onto a hostprocessor, the integration involving reuse of existing components on thehost system.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to anacoustic digitizer and a corresponding host.

At present, existing ultrasonic technologies are not embedded insidehosts, hosts being computing devices having a major function of theirown, including laptops, desktops, digital communication devices, digitalcameras etc. They are rather offered as “add on”s for what is called the“after market”.

Ultrasonic technology that overcomes the existing limitations ofultrasonic technology, has added value when embedded inside a computer.For example, microphones may be fixed on the housing of the host andlocations measured may be in relation to the computer.

One advantage is the ability to provide touch screen applications inwhich the location of the stylus can be measured in relation todifferent active regions or soft buttons on a screen. A furtheradvantage is that the computer casing can be constructed for paper to belocated in a determined way. The location measured by the microphonesfixed on the casing can then be understood in relation to the paper onwhich the user is writing.

A further advantage of embedding is that an embedded digitizer which hasaccess to an internal bus of the host can operate when the host is in adormant or standby state. Thus the digitizer could be used to wake thehost from the standby state, or to record writing when the computerremains otherwise dormant.

Ultrasonic location may be based on a signal issued by a pointing devicesuch as a stylus. In an embodiment the signal is a continuous signalcomprising a location signal modulated onto a continuous ultrasoundcarrier signal.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings. The invention is capable of otherembodiments or of being practiced or carried out in various ways.

Referring now to the drawings, FIG. 1 illustrates a computing system 10comprising a central processing unit (CPU) 12 and internal peripheraldevices 14.1, 14.2 etc such as memory devices of different kinds, soundcards, graphics cards, communications devices etc. An internal systembus 16 connects the internal peripheral devices to the CPU 12. One ofthe internal peripheral devices is an ultrasonic digitizer 18 thatdigitizes ultrasonic signals from associated microphones 20.1 . . .20.n. The ultrasonic signals are from an ultrasonic location device suchas a stylus, and the signals from the stylus are digitized to providethe current location of the stylus in relation to the speakers. Thedigitized output is provided to the system bus 14. The microphones mayin embodiments be fixed into the housing of the host computer.

In an embodiment, the system includes an internal codec. The codec maybe part of the CPU 12 or any of the peripheral devices. The ultrasonicdigitizer is connected to the internal codec and uses the internal codecto decode the locations. Typically the incoming ultrasound signal is acontinuous signal comprising a carrier wave and a modulation onto thecarrier wave. The codec may decode the modulations from the differentspeakers, say using cross-correlation, to accurately extract the time offlight from each speaker. The location can then be determined bytriangulation. The ability to make use of an internal codec is anadvantage of making the digitizer internal

Referring to FIG. 2, the ultrasonic signal may come from a stylus suchas stylus 30. Such a stylus may incorporate an ultrasonic transmitter 32inside a protective cage 34 and co-located with a pen tip 36 whichemerges from the cage for writing on a writing surface such as paper.

The stylus transmits its location to the associated microphones andallows user interaction with the computer system.

An additional transmitter 38 may be provided as desired at the far endof the stylus to provide information on the orientation of the stylus.

The writing tip may use ink, or any other writing medium such as pencilgraphite to write on the paper or other writing surface.

Referring now to FIG. 3, the stylus 40 transmits its location to twomicrophones 42 and 44, which in turn pass the signals to ultrasonicdigitizer 46.

The paper may be freely set at any location where the stylus is in rangeof the microphones. However accuracy is improved if the paper is set ata defined location so that the relationship between the paper and thelocation of the stylus is clear. The system may thus include anaccommodation assembly which accommodates paper or any other writingsurface in a defined relationship with the system.

Reference is now made to FIG. 4 which illustrates an example of such anaccommodation assembly. The accommodation assembly may be located in thehousing of the computer that hosts the system 10 with CPU 12, bus 16 andultrasonic device 18 described in the previous figures.

As shown in FIG. 4, a laptop housing 50 comprises moldings or moldedextrusions 52 which define the corners of common paper sizes. Paperplaced with the corners in the molded extrusions has a definedrelationship with microphones 54, which are also built into the housing50.

In general it is assumed that using writing as input and using thekeyboard as input are mutually exclusive, so in this embodiment thepaper location is over the top of the keyboard. A retractable hood maycover the area of the keyboard indicated by reference numeral 56 toconvert the area of the keyboard into a firm writing surface.

As an alternative to providing a hood, the screen flap 58 may be closedto provide a firm writing surface. Moldings such as those indicated by52 may also be placed on the back of the screen flap 58, and the usercan make notes which are stored on the computer without needing to openthe laptop. The laptop itself can be in a standby state, as will bediscussed below.

As shown in FIG. 4, there are sets of microphones on either side of thepaper. A selector may poll the microphones in each set, or may poll themicrophones individually and select those microphones which arereceiving a clearer signal for continued use. Thus say right and lefthanded users may obscure certain microphones when they are writing, andthe system may automatically switch to the best microphones for thecurrent user.

Reference is now made to FIGS. 5A and 5B. These figures illustrate afurther embodiment in which the papers are held in a defined locationbut not in a way that interferes with the computer itself. That is tosay the embodiment of FIGS. 5A and 5B relies on an external surface anddoes not obscure either the keyboard or screen, so the user can write onpaper and still use the keyboard and see the screen.

A clip 60 contains a receiver front 62 and an associated acoustic sensor64 and is tensioned by spring 66 against a surface 68. The housing 70 ofthe computer provides an alignment structure that defines an orientationfor the paper and the paper 72 is held within the alignment structure asshown in FIG. 5B. The configuration again holds the paper in a fixedrelationship with the microphones. The weight of the housing holds thepaper in position.

Reference is now made to FIGS. 6A and 6B. These figures illustrate analternative to the embodiment of FIGS. 5A and 5B in which the papers areheld in a defined location by a clip. In this case the clip is providedwith rotary tension. Again, the embodiment of FIGS. 6A and 6B relies onan external surface and does not obscure either the keyboard or screen,so the user can write on paper and still use the keyboard and see thescreen.

A clip 80 contains a lever 81 for manual raising of the clip toaccommodate paper. A receiver front 82 and an associated acoustic sensor84 are located in the body of the clip, which is tensioned by spring 86against a surface 88. The housing 90 of the computer provides analignment structure that defines an orientation for the paper and thepaper 92 is held within the alignment structure. The status of the paperbeing held is shown in FIG. 6B. The configuration holds the paper in afixed relationship with the microphones.

Housing 90 may include a holder for a stylus. In an embodiment theholder may include a recharging unit for recharging the stylus.

Reference is now made to FIG. 7, which shows an alternative embodimentof the paper alignment structure. In this case the paper alignmentstructure comprises a retractable paperweight 100. The microphones 102are built into the paperweight and the paperweight is attached via cord104 to the host computer 106. Cord 104 may be a serial cable connectsthe receiver to the host. In another embodiment, an “arm” with thesensors can unfold from the host's body. The paperweight 100 is placedover the paper or pad of paper 108. The underside of the paperweight mayinclude grooves 110 as shown in exaggerated manner in inset 112 toprecisely locate the corner of the paper.

After use the paperweight may be retracted into receptacle 114 in thehost computer.

Each of the above-described embodiments may be enhanced by adding asuitably placed additional microphone so that the triangulation can bein three dimensions. When using a pad of paper where the thicknessvaries, accuracy can be enhanced by being able to take into account thethickness of the pad. Additional embodiments may use the stylus to pointout edges and corners of three dimensional objects for input to a CADprogram or other programs that require three-dimensional input.

Reference is now made to FIG. 8, which is a schematic diagramillustrating an embodiment in which microphones 120 are placed in fixedarrangement to screen 122. The screen 122 displays active regions or asoft keyboard and the user operates stylus 124 in order to interact withthe screen. Since the microphones are built in to the housing, therelationship between the location that the microphones measure and theregions on the screen is accurately known.

As discussed above in connection with the closed screen embodiment,storage of writing data does not need the host computer to be in anactive state. Rather the host computer may be in a standby state inwhich many of the peripherals are switched off. Thus the user can writehis notes using the stylus when the computer is in standby. The computerstores the data which will later be available when the computer isswitched to an active state.

In an alternative embodiment, the digitizer comprises an on-board memorythat stores user input while the host computer is in a dormant state.The user input is then available for downloading to the computing systemwhen the computer is activated.

In yet an alternative embodiment the activation of the digitizer via thestylus switches the computing system from a dormant to an active state.

In most of the above embodiments it has been assumed that the paper isof a known size at a defined location. However it may not always beconvenient to place the paper in such a location. The system may thusinclude a calibration mechanism which detects the size and direction ofhandwriting and uses that to deduce a location or orientation of thepaper.

Issues relating to embedding a location digitizer, inside a hostmachine, whether for 2/D or 3/D locating, are now discussed in greaterdetail.

The ultrasonic digitizer/receiver 18-20 is embedded inside thehost/desktop/MID. The receiver picks up ultrasonic signals which aredigitized to 2/D, or 3/D coordinates.

The digitized data is interfaced to the main CPU by a system bus, suchas a serial digital connection, like USB, UART, SPI, I2C or any otherstandard serial bus. Alternatively, the data can be interfaced by aparallel connection using a PCI, PCMCIA etc. buses.

Certain applications may require a strict physical relation between thepaper or like writing surface and the receiver, thus necessitatingmapping actual A4 or other standard size paper to the computer. For thispurpose there may be provided a mechanical fixture to arrange such aconnection. The sensors, microphones or transducers, may be placed at aknown position in relation to the paper, at a pre-determined height,pre-determined location from the top of the paper and edges thereof etc.In particular, during the writing process, the paper ideally does notchange its location in relation to the sensors, as this would have theside-effect of introducing a shift of the digitized handwriting inrelation to the actual ink.

The placement of the microphones or other acoustic sensors may needacoustic engineering design, and may follow the guidelines as describedin applicant's copending International Patent Application No.IB2008/050946, filed Mar. 14, 2008, and more particularly to section 4.5in applicant's corresponding U.S. Provisional Patent Application No.60/906,813, filed 14 Mar. 2007, the contents of both of which are herebyincorporated by reference.

As discussed above, in one of the possible usage scenarios, the host maybe in standby mode, while the acoustic receiver is turned on, eitherperiodically or constantly, in order to pick up the acoustic or IRsignals. The activation of the transmitter triggers a sequence of eventsthat allows the host to process the data related to the transmission andthus digitize the location, storing the coordinate stream etc eventhough the host is otherwise in standby mode.

In an alternative embodiment, the receiver has its own memory to storethe data. When the host is activated, the user can view the data thatwas stored.

As discussed, one alternative usage model is to regard the host as apaper pad while the host is in a folded state. One of its flat sides,say the bottom side of the host or the back of the screen, may beregarded as a table, and sensors may be provided thereon to pick up thesignals when writing on the particular side of the housing.

In a further alternative, a plastic pad can be unfolded from the host toallow a pre-determined working area.

Another option, as discussed above, is to cover the keyboard with aretractable hood that in its extended state serves as a flat surface forwriting.

Another option is to provide a digitization area in front of thekeyboard, in like manner to the mouse finger pad that many hosts have.

The digitizer may be used for signature biometric authentication. Inorder to log on to the host computer, a user may be prompted to sign,thus allowing security without requiring the user to memorize apassword.

In a further embodiment, when the user folds the screen, the digitizermay change its function automatically. For instance, when the screen isopen, it may function as a mouse, and when it closes, it may start tosave notes into a file.

In order to facilitate the usage of the technology, sensors may beembedded on the perimeter of the host. Sensors are then sampledperiodically in order to find the area where the stylus is sending thesignals. Once finding the closest sensors to the transmitted signals,other sensors may be ignored. This way, the host is able to adjustdynamically to left and right handed users.

As mentioned, if the user does not place the A4 paper firmly in thelocations provided, there is an option for the computer software tocalibrate virtual paper to accommodate the handwriting. The inputs forsuch a calibration process may include an area bounding the handwriting,and also the direction of the writing, which may imply the direction oforientation of the paper.

In order to save the cost of hardware components inside the host, thereceiver's hardware may share some of the sensors with other functionalblocks of the host. Such is true for both an IrDA sensor, and for themicrophones.

The sharing of components gives rise to two embodiments, a moduleintegration embodiment and a deep integration embodiment. The moduleintegration embodiment is in general as described above, and uses USB,UART, SPI buses and the like to pass coordinates, or at least a digitalaudio signal carrying the coordinates, to the central processor. In analternative embodiment, instead of coordinates, the audio data thatexits the CODEC may be output to the bus to pass to the centralprocessor.

The deep integration embodiment uses the host's native interface tosample the EPOS signals. A proposed architecture is as shown in FIG. 9.

FIG. 9 shows a basic architecture, in which a host 130 comprises amostly digital unit manufactured with a small silicon process in orderto make it as small as possible. A CODEC 134 forms a companion to theprocessor, coprocessor, which takes care of most of the analog signalconditioning, for example voltage regulation, ADC, say for microphonesinput, DAC, say for output to speakers, vibration etc. Because of theanalog nature of the CODEC 134, it is usually manufactured using alarger geometry than the main processor 132. In some cases, the CODECfunctionality may be integrated into the processor 132 itself. SinceCODECs are manufactured to support audio frequencies, they are oftenoptimized for input signals which are below 20 KHz. For ultrasonics,such a frequency range is not sufficient and the CODEC in use needs tosupport enough resolution at ultrasonic frequencies, say above 40 dB at50 KHz (a typical example). FIG. 9 shows an embodiment with two dualband microphones 96.

Reference is now made to FIG. 10, which is a simplified diagram showingthe host of FIG. 9 with an additional wireless or IR receiver 138,already providing the synchronization link, to additionally incorporatea third microphone. If there are three microphones, there is enoughinformation to decode the position of the transmitter. However, theusage of 3 microphones and no data link incorporates additional problemssuch as encoding the data on the acoustic signal (data can be switchstatus on the pen side). As shown, an IR or RF link 138 supports bothsynchronization and data transfer. The block diagram in this case willbe:

The wireless link 138 may use a protocol which is already supported bythe host, such as Bluetooth, WiFi, etc or a subset of those.

There is an inherent issue in this architecture for synchronization:each of the blocks has its own clock source; yet it is necessary tosynchronize the software which runs on the processor so that theprocessor is synchronized with the transmitter (not shown).

The synchronization is performed in 2 phases:

1) CODEC to CPU Synchronization:

Upon an overflow of the acoustic samples buffer, an internal interruptis generated. The ISR that handles this interrupt, reads the freerunning timer value to obtain a time stamp. Since this interrupt may bemasked by higher priority processes, the jittering of the timer valuemay be relatively large. However, this process may start way before thelocation application begins to run, so any resulting timing errors maybe filtered by the passing of sufficient data.

2) Transceiver to CPU Synchronization:

Upon receiving a valid packet by the transceiver 138, which as mentionedmay be RF or IR, an interrupt is generated. The ISR that handles theinterrupt reads the free running timer value to obtain a time stamp.This interrupt should be with the highest priority, so the jittering ofthe time stamp due to software execution will be minimal.

An additional approach is to use digital microphones (DMIC). However itmay be that the internal CODEC does not support the ultrasonic range.The straight forward approach is thus to use the architecture shown inFIG. 11. FIG. 11 shows a decimation filter 140 connected between thedual band microphones and the host processor in parallel with the Codec.

The CODEC 134 provides the clock signals to the microphones, and also tothe dedicated “Decimation Filter” ASIC 140. The outputs of the DMICs 136are routed both to the CODEC and to the ASIC 140. The output of the ASIC140 is interfaced to the host 132 by a serial interface such as UART,I2S, SPI etc.

A receiver module according to the above embodiments, may be used toenable a touchscreen application, as discussed in respect of FIG. 8hereinabove. The screen may include soft buttons and active areas butrather than the screen actually being a touchscreen and sensing thestylus, the digitizer detects its location over the active areas andinterprets the interaction accordingly.

The addition of a 3rd microphone to the host as discussed above,particularly with respect to FIG. 10, may enable numerous kinds ofapplications using 3/D data. Several specific ideas are mentioned herebut in non-limiting manner:

1. Handwriting: compensating for the height of the paper.

2. 3/D gestures: a 3/D device can transfer the 2/D working environmentof the screen to a 3/D environment.

3. 3/D applications: mechanical design, graphical design, gaming.

The stylus may further serve as a remote control, sending commands tothe host such as: play, page up, page down etc.

When the host screen is folded, the stylus may change its function andstart to control a 2nd device, such as a projector.

The calibration of a receiver as described herein is preferably carriedout prior to being assembled inside a host. In one approach, thereceiver is calibrated, with its acoustic front, at the module level.Therefore, the module should be designed to enable such a calibration.

A further embodiment uses a wired pen. In this case the synchronizationneeded is just between the CPU and its CODEC.

An Interface IC may be used. Such an interface IC may be a dedicated IC,or an off the shelf component such as an EEPROM. An EEPROM can output ina periodic manner a waveform that is encoded digitally, for examplesigma delta format. A passive network may interface the pen and ICnetwork to the ultrasonic transmitter.

An additional embodiment includes a temperature sensor as part of thepositioning mechanism. The temperature sensor allows for the positioningsystem to compensate for measurement inaccuracies of various kindscaused by temperatures and associated offsets, and thus improve thepositioning accuracy. One of the sources of temperature-based inaccuracyis that the speed of sound depends on temperature. Thus temperaturecompensation adds accuracy to the application.

The pointing device, stylus, pen etc, may be battery powered and may berechargeable.

Reference is now briefly made to FIG. 12, which illustrates apositioning according to the embodiments described above. A host systemintegrates the position by use of its existing components. An existinghost processor 132 and CODEC 134 perform the functions that thepositioning system requires.

A pressure sensor may digitize the pressure the user puts on the pen.Such digitizing may add a more ‘realistic’ feedback to the digitalrepresentation. The pressure data may be passed through the IR/Rf link,or alternatively may be modulated, along with the positioning data, ontothe ultrasound signal.

The term “stylus” is used herein to refer to any pointing device used asa locator which sends an ultrasonic signal. The stylus may be wireless.

It is expected that during the life of a patent maturing from thisapplication many relevant digitization technologies will be developedand the scope of related terms such as “digitizer” are intended toinclude all such new technologies a priori.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”. This termencompasses the terms “consisting of” and “consisting essentially of”.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

What is claimed is:
 1. A computing system for determining a location ofa positioning device, the computing system comprising: a processorhaving a system clock; a CODEC external to said processor, said CODECbeing configured to decode ultrasonic signals of said positioning devicereceived via at least two microphones to provide said processor with apositioning signal further processable to determine said location; and asynchronizing unit for synchronizing said CODEC with said system clock.2. The computing system of claim 1, further comprising a filter inparallel with said CODEC.
 3. The computing system of claim 1 wherein:said CODEC is further configured to determine a time of flight of eachof said ultrasonic signals; and the processor is configured to determinesaid location based on triangulation using said time of flight of eachof said ultrasonic signals.
 4. The computing system of claim 1 whereinsaid ultrasonic signals comprise a location signal modulated onto acontinuous ultrasonic carrier.
 5. The computing system of claim 1,further comprising a screen and wherein said at least two microphonesare fixed about said screen to provide a touchscreen application.
 6. Thecomputing system of claim 1, further comprising a wireless transceiverfor wireless networking, wherein said synchronization unit furthersynchronizes said wireless transceiver with said system clock.
 7. Thecomputing system of claim 1, further comprising: an accommodationassembly for accommodating paper in a defined relationship with saidcomputing system; and a housing, wherein said paper accommodation systemcomprises a paper alignment structure, said paper alignment structurecomprising a configuration that holds paper in a fixed relationship withsaid at least two microphones.
 8. The computing system of claim 7wherein said paper alignment structure is built onto said housing. 9.The computing system of claim 7 wherein said paper alignment structurecomprises a first set of at least two microphones about one side thereofand a second set of at least two microphones about a second side thereofand a selector for selecting between said first and said second sets ofat least two microphones depending on which set are receiving a clearersignal.
 10. The computing system of claim 1, further comprising ahousing, wherein said housing comprises a recharging holder for saidpositioning device.
 11. The computing system of claim 1, furthercomprising a third microphone for three-dimensional location of saidpositioning device.
 12. The computing system of claim 11 configured touse said three-dimensional location to compensate for a height of paperin determining said location.
 13. The computing system of claim 1configured such that activation of said positioning unit switches saidcomputing system from a dormant state to an active state.
 14. Thecomputing system of claim 1, further comprising a positioning unitcomprising a memory that stores user input while said computing systemis in a dormant state, which user input is subsequently accessible bysaid computing system.
 15. The computing system of claim 1, furthercomprising a positioning unit configured to accept input while saidcomputing system remains in an otherwise dormant state.
 16. Thecomputing system of claim 1, further comprising a computer housing andwherein said at least two microphones are in a fixed relationship withrespect to said housing.
 17. The computing system of claim 1, furthercomprising a system bus coupled to said processor, wherein saidpositioning signal is sent to said processor using said system bus. 18.A method of determining a location of a positioning device, the methodcomprising: receiving ultrasonic signals from said positioning deviceusing at least two microphones; decoding said ultrasonic signals usingan external CODEC to generate a positioning signal; processing saidpositioning signal to determine said location of said positioningdevice; and synchronizing said external CODEC with a processor clock.19. The method of claim 18, further comprising filtering said ultrasonicsignals in parallel with said decoding.
 20. The method of claim 18wherein determining said location of said positioning device comprises:determining a time of flight of each of said ultrasonic signals; anddetermining said location based on triangulation using said time offlight of each of said ultrasonic signals.
 21. The method of claim 18,further comprising outputting said positioning signal over a bus to aprocessor, wherein said processor performs said processing.
 22. Acomputing system comprising: processing means having a clock; anddecoding means external to said processing means, said decoding meanscomprises a synchronizing means; wherein said decoding means comprisesmeans for decoding ultrasonic signals received from a positioning meansvia at least two sensing means and means for providing said processingmeans with a positioning signal; wherein said processing means comprisesmeans for processing said positioning signal to determine acorresponding positioning device location; and wherein saidsynchronizing means comprises means for synchronizing said decodingmeans with said clock.
 23. The computing system of claim 22, furthercomprising a filtering means in parallel with said decoding means. 24.The computing system of claim 22, further comprising a display means andwherein said at least two sensing means are fixed about said displaymeans to provide a touchscreen application.
 25. A computing systemcomprising: a processor having a clock; internal peripheral devices; aCODEC external to said processor; and a system bus connecting saidinternal peripheral devices to said processor; wherein: one of saidinternal peripheral devices is configured to receive informationassociated with ultrasonic signals from at least two associatedmicrophones and output a digitized audio output as a signal on saidsystem bus; said digitized audio output comprises a decoded positioningdevice location; said one of said internal peripheral devices is coupledto said CODEC to use said CODEC to decode said location; and said CODECis synchronized with said clock.
 26. The computing system of claim 25,further comprising a filter in parallel with said CODEC.
 27. Thecomputing system of claim 25 wherein said ultrasonic signals comprise alocation signal modulated onto a continuous ultrasonic carrier.
 28. Thecomputing system of claim 25, further comprising: a wireless unitconfigured for wireless networking; and a synchronization unitconfigured to synchronize said CODEC with said clock and synchronizesaid wireless unit with said clock.